Instead of simply propagating an error verbatim, we sometimes want to
add to its message, like this:
frobnicate(arg, &err);
error_setg(errp, "Can't frobnicate %s: %s",
arg, error_get_pretty(err));
error_free(err);
This is suboptimal, because it loses err's hint (if any). Moreover,
when errp is &error_abort or is subsequently propagated to
&error_abort, the abort message points to the place where we last
added to the error, not to the place where it originated.
To avoid these issues, provide means to add to an error's message in
place:
frobnicate(arg, errp);
error_prepend(errp, "Can't frobnicate %s: ", arg);
Likewise, reporting an error like
frobnicate(arg, &err);
error_report("Can't frobnicate %s: %s", arg, error_get_pretty(err));
can lose err's hint. To avoid:
error_reportf_err(err, "Can't frobnicate %s: ", arg);
The next commits will put these functions to use.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1450452927-8346-10-git-send-email-armbru@redhat.com>
While there, tighten error_append_hint()'s assertion.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1450452927-8346-6-git-send-email-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Suggested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1447776349-2344-1-git-send-email-armbru@redhat.com>
When munging enum values, the fact that we were passing the entire
prefix + value through camel_to_upper() meant that enum values
spelled with CamelCase could be turned into CAMEL_CASE. However,
this provides a potential collision (both OneTwo and One-Two would
munge into ONE_TWO) for enum types, when the same two names are
valid side-by-side as QAPI member names. By changing the generation
of enum constants to always be prefix + '_' + c_name(value,
False).upper(), and ensuring that there are no case collisions (in
the next patches), we no longer have to worry about names that
would be distinct as QAPI members but collide as variant tag names,
without having to think about what munging the heuristics in
camel_to_upper() will actually perform on an enum value.
Making the change will affect enums that did not follow coding
conventions, using 'CamelCase' rather than desired 'lower-case'.
Thankfully, there are only two culprits: InputButton and ErrorClass.
We already tweaked ErrorClass to make it an alias of QapiErrorClass,
where only the alias needs changing rather than the whole tree. So
the bulk of this change is modifying INPUT_BUTTON_WHEEL_UP to the
new INPUT_BUTTON_WHEELUP (and likewise for WHEELDOWN). That part
of this commit may later need reverting if we rename the enum
constants from 'WheelUp' to 'wheel-up' as part of moving
x-input-send-event to a stable interface; but at least we have
documentation bread crumbs in place to remind us (commit 513e7cd),
and it matches the fact that SDL constants are also spelled
SDL_BUTTON_WHEELUP.
Suggested by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1447836791-369-27-git-send-email-eblake@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
The qapi enum ErrorClass is unusual that it uses 'CamelCase' names,
contrary to our documented convention of preferring 'lower-case'.
However, this enum is entrenched in the API; we cannot change
what strings QMP outputs. Meanwhile, we want to simplify how
c_enum_const() is used to generate enum constants, by moving away
from the heuristics of camel_to_upper() to a more straightforward
c_name(N).upper() - but doing so will rename all of the ErrorClass
constants and cause churn to all client files, where the new names
are aesthetically less pleasing (ERROR_CLASS_DEVICENOTFOUND looks
like we can't make up our minds on whether to break between words).
So as always in computer science, solve the problem by some more
indirection: rename the qapi type to QapiErrorClass, and add a
new enum ErrorClass in error.h whose members are aliases of the
qapi type, but with the spelling expected elsewhere in the tree.
Then, when c_enum_const() changes the munging, we only have to
adjust the one alias spot.
Suggested by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1447836791-369-26-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
We have several tests that perform multiple sub-actions that are
expected to fail. Asserting that an error occurred, then clearing
it up to prepare for the next action, turned into enough
boilerplate that it was sometimes forgotten (for example, a number
of tests added to test-qmp-input-visitor.c in d88f5fd leaked err).
Worse, if an error is not reset to NULL, we risk invalidating
later use of that error (passing a non-NULL err into a function
is generally a bad idea). Encapsulate the boilerplate into a
single helper function error_free_or_abort(), and consistently
use it.
The new function is added into error.c for use everywhere,
although it is anticipated that testsuites will be the main
client.
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Similar to error_abort, but doesn't report where the error was
created, and terminates the process with exit(1) rather than abort().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1441983105-26376-2-git-send-email-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Commits 7216ae3d and d2828429 disabled some error message hints,
all because a change to use modern error reporting meant that the
hint would be output prior to the actual error. Fix this by making
hints a first-class member of Error.
For example, we are now back to the pleasant:
$ qemu-system-x86_64 --nodefaults -S --vnc :0 --chardev null,id=,
qemu-system-x86_64: --chardev null,id=,: Parameter 'id' expects an identifier
Identifiers consist of letters, digits, '-', '.', '_', starting with a letter.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1441901956-21991-1-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
This is particularly useful when we abort in error_propagate(),
because there the stack backtrace doesn't lead to where the error was
created. Looks like this:
Unexpected error in parse_block_error_action() at .../qemu/blockdev.c:322:
qemu-system-x86_64: -drive if=none,werror=foo: 'foo' invalid write error action
Aborted (core dumped)
Note: to get this example output, I monkey-patched drive_new() to pass
&error_abort to blockdev_init().
To keep the error handling boiler plate from growing even more, all
error_setFOO() become macros expanding into error_setFOO_internal()
with additional __FILE__, __LINE__, __func__ arguments. Not exactly
pretty, but it works.
The macro trickery breaks down when you take the address of an
error_setFOO(). Fortunately, we do that in just one place: qemu-ga's
Windows VSS provider and requester DLL wants to call
error_setg_win32() through a function pointer "to avoid linking glib
to the DLL". Use error_setg_win32_internal() there. The use of the
function pointer is already wrapped in a macro, so the churn isn't
bad.
Code size increases by some 35KiB for me (0.7%). Tolerable. Could be
less if we passed relative rather than absolute source file names to
the compiler, or forwent reporting __func__.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
qga_vss_fsfreeze() casts error_set_win32() from
void (*)(Error **, int, ErrorClass, const char *, ...)
to
void (*)(void **, int, int, const char *, ...)
The result is later called. Since the two types are not compatible,
the call is undefined behavior. It works in practice anyway.
However, there's no real need for trickery here. Clean it up as
follows:
* Declare struct Error, and fix the first parameter.
* Switch to error_setg_win32(). This gets rid of the troublesome
ErrorClass parameter. Requires converting error_setg_win32() from
macro to function, but that's trivially easy, because this is the
only user of error_set_win32().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
I've typed error_report("%s", error_get_pretty(ERR)) too many times
already, and I've fixed too many instances of qerror_report_err(ERR)
to error_report("%s", error_get_pretty(ERR)) as well. Capture the
pattern in a convenience function.
Since it's almost invariably followed by error_free(), stuff that into
the convenience function as well.
The next patch will put it to use.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Add a special Error * that can be passed to error handling APIs to
signal that any errors are fatal and should abort QEMU. There are two
advantages to this:
- allows for brevity when wishing to assert success of Error **
accepting APIs. No need for this pattern:
Error * local_err = NULL;
api_call(foo, bar, &local_err);
assert_no_error(local_err);
This also removes the need for _nofail variants of APIs with
asserting call sites now reduced to 1LOC.
- SIGABRT happens from within the offending API. When a fatal error
occurs in an API call (when the caller is asserting sucess) failure
often means the API itself is broken. With the abort happening in the
API call now, the stack frames into the call are available at debug
time. In the assert_no_error scheme the abort happens after the fact.
The exact semantic is that when an error is raised, if the argument
Error ** matches &error_abort, then the abort occurs immediately. The
error messaged is reported.
For error_propagate, if the destination error is &error_abort, then
the abort happens at propagation time.
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
These functions help maintaining homogeneous formatting of error messages
with Windows error code and description (generated by
g_win32_error_message()).
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
